Kif4 regulates the expression of VEGFR1 through the PI3K/Akt signaling pathway in RAW264.7 monocytes/macrophages.

Abstract

Kinesin superfamily protein4(Kif4), a microtubule-based motor protein, has been shown to participate in a number of critical cellular processes, such as cell division, the intracellular transport of membranous vesicles and signal transduction. However, whether KIF4 regulates vascular endothelial growth factor(VEGF) receptor1(VEGFR1) expression remains unknown. Thus, in this study, in order to examine the effects of Kif4 on the expression of VEGFR1 in RAW264.7 monocytes/macrophages, Kif4 was silenced using siRNA. RT-qPCR, western blot analysis and ELISA were used to assess the expression of Kif4 and VEGFR1 up- and downstream signaling molecules, including VEGF-A, VEGFR1, soluble form of VEGFR1(sVEGFR1), phosphorylated(p-)Akt and Akt. The silencing Kif4 inhibited the mRNA expression of VEGF(P<0.01) and p-Akt(P<0.05); however, the level of VEGF-A was increased(P<0.05) compared with the negative control siRNA-transfected group. The silencing of Kif4 decreased the VEGFR1 mRNA(P<0.05), VEGFR1 protein and sVEGFR1 levels in the cell supernatant(P<0.01). Following the application of insulin-like growth factor-1(100ng/ml), the specific agonist of PI3K/Akt in the Kif4siRNA-transfected group,the VEGFR1 mRNA levels(P<0.001), the VEGFR1 protein levels and the sVEGFR1(P<0.01) levels significantly increased; however, the levels of VEGF in the cell supernatant were decreased(P<0.05). Taken together, these findings suggest that Kif4 regulates the expression of VEGFR1 in RAW264.7cells and that the PI3K/Akt pathway is involved in this process.